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Bluetooth

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This article is about the Bluetooth wireless specification. For King Harald Bluetooth, see Harald I of Denmark.

Bluetooth logo

Bluetooth is an industrial specification for wireless personal area networks (PANs), also known as IEEE 802.15.1. Bluetooth provides a way to connect and exchange information between devices like personal digital assistants (PDAs), mobile phones, laptops, PCs, printers, digital cameras and video game consoles via a secure, globally unlicensed short-range radio frequency.

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Etymology

The name Bluetooth is derived from the cognomen of a 10th century king of Denmark, Harald Bluetooth. According to the inventors of the Bluetooth technology, Harald engaged in diplomacy which led warring parties to negotiate with each other, making Bluetooth a fitting name for their technology, which allows different devices to talk to each other.[1]. The name of the king in Danish is Harald Blåtand and the Bluetooth logo is based on the H and B runes.

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Introduction

A typical Bluetooth mobile phone headset

A typical Bluetooth USB adapter

Bluetooth is a radio standard and communications protocol primarily designed for low power consumption, with a short range (power class dependent: 1 meter, 10 meters, 100 meters) based around low-cost transceiver microchips in each device.

Bluetooth lets these devices communicate with each other when they are in range. The devices use a radio communications system, so they do not have to be in line of sight of each other, and can even be in other rooms, so long as the received transmission is powerful enough. As a result of different antenna designs, transmission path attenuations, and other variables, observed ranges are variable; however, transmission power levels must fall into one of three classes:

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Bluetooth applications

• Wireless control of and communication between a cell phone and a hands free headset or car kit. This is the most popular use.

• Wireless networking between PCs in a confined space and where little bandwidth is required.

• Wireless communications with PC input and output devices, the most common being the mouse, keyboard and printer.

• Transfer of files between devices via OBEX.

• Transfer of contact details, calendar appointments, and reminders between devices via OBEX.

• Replacement of traditional wired serial communications in test equipment, GPS receivers and medical equipment.

• For remote controls where infrared was traditionally used.

• Sending small advertisements from Bluetooth enabled advertising hoardings to other, discoverable, Bluetooth devices.

• Wireless control of a games console, Nintendo's Wii and Sony's PlayStation 3 will both use Bluetooth technology for their wireless controllers.

• Sending commands and software to the LEGO Mindstorms NXT instead of infrared.

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Bluetooth vs. Wi-Fi in today’s networked world

Bluetooth and Wi-Fi both have their places in today’s offices, homes and on the move: setting up networks, printing, or transferring presentations and files from PDAs to computers.

Bluetooth

Bluetooth is in a variety of new products such as phones, printers, modems, and headsets, to name a few. Bluetooth is acceptable for situations when two or more devices are in close proximity with each other and don't require high bandwidth. Bluetooth is most commonly used with cell phones and handheld computing devices, either using a Bluetooth headset or transferring files from phones/PDAs to computers. Since Bluetooth uses short-range radio frequencies, it is not as effective for setting up networks that can be accessed from remote locations as with Wi-Fi.

Bluetooth also simplified the discovery and setup of services. Wi-Fi is more analogous to the traditional Ethernet network, and requires configuration to set up shared resources, transmit files, set up audio links (e.g. headsets and hands-free devices), whereas Bluetooth devices advertise all services they actually provide; this makes the utility of the service that much more accessible, without the need to worry about network addresses, permissions and all the other considerations that go with typical networks.

Wi-Fi

Wi-Fi uses the same radio frequencies as Bluetooth, but with higher power consumption resulting in a stronger connection. As mentioned earlier, Wi-Fi is sometimes called "wireless ethernet". Although this description is inaccurate, it provides an indication of Wi-Fi's capabilities.^{[verification needed]} Wi-Fi is better suited for setting up networks as it enables a faster connection and has better security than Bluetooth. Wi-Fi is also becoming increasingly popular and widespread; it is a standard feature of most new laptop computers, and is a straightforward expansion to desktop computers not already Wi-Fi enabled (eg. through the use of a USB dongle).

As a traditional networking medium, Wi-Fi is more versatile, but harder to configure. Most users need good know-how (or an IT department) to get things set up, especially when using more obscure services such as audio and HID. For this reason, Wi-Fi falls well short of the standard for ad-hoc networking, one of the basic tenets of the Bluetooth framework. [2]

One method for comparing the efficiency of wireless transmission protocols such as Bluetooth and Wi-Fi is called spatial capacity.

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Specifications and Features

The Bluetooth specification was first developed in 1994 by Jaap Haartsen, who was working for Ericsson Radio Systems located in Emmen in The Netherlands. The specifications were formalized by the Bluetooth Special Interest Group (SIG). The SIG was formally announced on May 20, 1999. Today it has over 1800 companies worldwide. It was established by Ericsson, Sony Ericsson, IBM, Intel, Toshiba and Nokia, and later joined by many other companies as Associate or Adopter members. Bluetooth is also known as IEEE 802.15.1.

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Bluetooth 1.0 and 1.0B

Versions 1.0 and 1.0 B had many problems and the various manufacturers had great difficulties in making their products interoperable. 1.0 and 1.0B also had mandatory Bluetooth Hardware Device Address (BD_ADDR) transmission in the handshaking process, rendering anonymity impossible at a protocol level, which was a major setback for services planned to be used in Bluetooth environments, such as Consumerium.

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Bluetooth 1.1

• Many errors found in the 1.0B specifications were fixed.

• Added support for non-encrypted channels.

• Received Signal Strength Indicator (RSSI)

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Bluetooth 1.2

This version is backwards compatible with 1.1 and the major enhancements include

• Adaptive Frequency-hopping spread spectrum (AFH), which improves resistance to radio frequency interference by avoiding the use of crowded frequencies in the hopping sequence

• Higher transmission speeds in practice

• extended Synchronous Connections (eSCO), which improves voice quality of audio links by allowing retransmissions of corrupted packets.

• Host Controller Interface (HCI) support for 3-wire UART

• HCI access to timing information for Bluetooth applications:

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Bluetooth 2.0

This version is backwards compatible with 1.x. The main enhancement is the introduction of Enhanced Data Rate (EDR) of 3.0 Mbps. This has the following effects (Bluetooth SIG, 2004):

• 3 times faster transmission speed (up to 10 times in certain cases).

• Lower power consumption through a reduced duty cycle.

• Simplification of multi-link scenarios due to more available bandwidth.

• Further improved BER (bit error rate) performance.

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Future of Bluetooth

The next version of Bluetooth technology, currently code-named Lisbon, includes a number of features to increase security, usability and value of Bluetooth. The following features are defined:

• Atomic Encryption Change - allows encrypted links to change their encryption keys periodically, increasing security, and also allowing role switches on an encrypted link.

• Extended Inquiry Response - provides more information during the inquiry procedure to allow better filtering of devices before connection. This information includes the name of the device, and a list of services, with other information.

• Sniff Subrating - reducing the power consumption when devices are in the sniff low-power mode, especially on links with asymmetric data flows. Human interface devices (HID) are expected to benefit the most, with mice and keyboards increasing the battery life from 3 to 10 times those currently used.

• QoS Improvements - these will enable audio and video data to be transmitted at a higher quality, especially when best effort traffic is being transmitted in the same piconet.

• Simple Pairing - this improvement will radically improve the pairing experience for Bluetooth devices, while at the same time increasing the use and strength of security. It is expected that this feature will significantly increase the use of Bluetooth.

Bluetooth technology already plays a part in the rising Voice over IP (VOIP) scene, with Bluetooth headsets being used as wireless extensions to the PC audio system. As VOIP becomes more popular, and more suitable for general home or office users than wired phone lines, Bluetooth may be used in Cordless handsets, with a base station connected to the Internet link.

The version of Bluetooth after Lisbon, code-named Seattle, has many of the same features, but is most notable for plans to adopt Ultra-wideband radio technology. This will allow Bluetooth use over UWB radio, enabling very fast data transfers, synchronizations and file pushes, while building on the very low power idle modes of Bluetooth. The combination of a radio using little power when no data is transmitted, and a high data rate radio used to transmit bulk data, could be the start of software radios. Bluetooth, given its worldwide regulatory approval, low power operation, and robust data transmission capabilities, provides an excellent signalling channel to enable the soft radio concept.

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